VTE risk after bariatric surgery should be assessed

SEATTLE – Preop thromboelastometry can identify patients who need extra anticoagulation against venous thromboembolism following bariatric surgery, according to a prospective investigation of 40 patients at Conemaugh Memorial Medical Center in Johnstown, Pa.

Enoxaparin 40 mg twice daily just wasn’t enough for people who were hypercoagulable before surgery. The goal of the study was to find the best way to prevent venous thromboembolism (VTE) after weight loss surgery. At present, there’s no consensus on prophylaxis dosing, timing, duration, or even what agent to use for these patients. Conemaugh uses postop enoxaparin, a low-molecular-weight heparin. Among many other options, some hospitals opt for preop dosing with traditional heparin, which is less expensive.

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The Conemaugh team turned to thromboelastometry (TEM) to look at the question of VTE risk in bariatric surgery patients. The test gauges coagulation status by measuring elasticity as a small blood sample clots over a few minutes. The investigators found that patients who were hypercoagulable before surgery were likely to be hypercoagulable afterwards. The finding argues for baseline TEM testing to guide postop anticoagulation.

The problem is that bariatric services don’t often have access to TEM equipment, and insurance doesn’t cover the $60 test. In this instance, the Lake Erie College of Osteopathic Medicine in Erie, Pa., had the equipment and covered the testing for the study.

The patients had TEM at baseline and then received 40 mg of enoxaparin about 4 hours after surgery – mostly laparoscopic gastric bypasses – and a second dose about 12 hours after the first. TEM was repeated about 2 hours after the second dose.

At baseline, 2 (5%) of the patients were hypocoagulable, 15 (37.5%) were normal, and 23 (57.5%) were hypercoagulable. On postop TEM, 17 patients (42.5%) were normal and 23 (57.5%) were hypercoagulable: “These 23 were inadequately anticoagulated,” said lead investigator Daniel Urias, MD, a general surgery resident at the medical center.

“There was an association between being normal at baseline and being normal postop, and being hypercoagulable at baseline and hypercoagulable postop. We didn’t anticipate finding such similarity between the numbers. Our suspicion that baseline status plays a major role is holding true,” Dr. Urias said at the World Congress of Endoscopic Surgery hosted by SAGES & CAGS.